Manipulators, in particular industrial robots, are used for various work processes in, for example, assembly or production in industrial environments. Industrial robots are automatically controlled machines equipped with three or more freely programmable movement axes, which are equipped with appropriate tools for the automatic manipulation of objects.
The use of several manipulators, for example, robots, which share the same working space (or workplace, working range), can increase productivity. However, a working space should not be used by several manipulators at the same time, as this can lead to collisions. For this reason, a manipulator or its controller checks, usually before it enters into a defined common working space, at the limit of the working space, that the working space is not occupied and is thus vacant. If the working space is not vacant, the manipulator conventionally decelerates directly before reaching the working space limit. Only when the working space is vacated, does the manipulator accelerate again and enter into the working space. This method has certain disadvantages, in particular, it leads to undesired manipulator down time. In addition, the deceleration and acceleration consumes additional energy and increases the stress on the manipulator.
In the patent document US 2009/0204258 A1 published in the English language on Aug. 13, 2009 and hereby incorporated by reference in its entirety herein, a system and a method are described to control a plurality of robots on a rail. To prevent the robots from colliding, it is proposed to monitor dynamic spaces of the robots, and to halt a robot in the event of overlap of these spaces.
Furthermore, the patent document US 2013/0110288 A1 published in the English language on May 2, 2013 and hereby incorporated by reference in its entirety herein, proposes modelling the working space of every robot, and defining one or more interference areas. The interference areas should be classified either as “prohibited”, “monitored” or “hybrid”. The status of a hybrid interference area is dynamically toggled for each robot between “prohibited” and “monitored”, depending on whether the hybrid area is free of other robots.
The U.S. Pat. No. 7,765,031 B2, published in the English language on Jul. 27, 2010 and hereby incorporated by reference in its entirety herein, relates to a method for avoiding an interference between a plurality of robots in an overlapping section between occupation zones of a plurality of robots. Furthermore, the patent specification describes a robot which is able to avoid an interference with another robot in an overlapping section between the occupation zones of the robot and of the other robot.
It is thus known from the prior art to identify working space violations and, if necessary, to stop the movement of a manipulator, in order to avoid collisions.
In view of the above-explained prior art, the objective of the present invention is to provide a method and a system which permits better use of a working space by several manipulators, and thereby eliminates or minimizes the above-mentioned disadvantages. The objective is achieved with the method according to claim 1 and the manipulator system according to claim 10.